Embodiments of the present invention generally relate to a cooling system for electric rotor machines. More particularly, embodiments of the present invention relate to a symmetrical cooling system for electric rotor machines.
Electric rotor machines, including, for example, electric motors and generators, generate heal that is often associated with electrical and mechanical losses within the electric rotor machines. The amount of heat generated by a particular electric rotor machine may depend on a variety of different factors, including, for example, the size of the load on the electric rotor machine and the frequency of the starting and braking of the electric rotor machine, among other factors.
Cooling of electric rotor machines is often necessary so as to at least attempt to prevent the occurrence of a variety of heat-induced issues, including, for example, short circuits and winding burnout and failure, among other heat related issues that may hinder the operation, and/or shorten the life span, of electric rotor machines. Cooling of electric rotor machines often involves transferring the heat generated by the electric rotor machine to a cooling medium, such as, for example, air. Such heat transfer may often utilize an asymmetrical type cooling system wherein a fan induces flow of cooling air generally across the entire length of an interior region of the electric rotor machine or the entire length of a stator within the interior region. However, such asymmetrical type cooling systems tend to have notable temperature differences between the ends of the electric rotor machine. More specifically, as the cooling medium that entered the first end of the electric rotor machine flows along the length of the electric rotor machine, and accumulates loss energy in the form of heat, the temperature of the cooling medium increases. Thus, the temperature of the cooling medium that arrives at the second end of the electric rotor machine is, typically, notably higher than the temperature the cooling medium has at the first end. As a consequence, the ability of the heated cooling medium at the second end to remove heat is often diminished, which may lead to relatively significant temperature gradients between the first and second ends of the electric rotor machine.